Utility meters, including for example electricity, gas, water and oil meters, operate to measure the consumption of a commodity by a residence, factory, commercial establishment or other such facility. Utility service providers employ utility meters to track individual customers' usage of the utility-provided commodities. Utilities track customer usage for many purposes, including billing and tracking demand for the commodity.
Referring specifically to electricity meters, electricity meters have historically measured energy consumption using electromechanical hardware, such as an arrangement of rotating disks. Such meters are still in widespread use. In these meters, the rotating disks are driven by electromagnetic forces generated by signals produced in the measurement circuits of the meter. The rotations of the disk are recorded in a register. One type of meter register, an electromechanical registers, consists of numbered dials driven by gears. One drawback of meters having electromechanical registers is that the energy consumption data must be manually obtained from the physical meter device. In other words, electromechanical registers require that utility providers employ field technicians, or “meter-readers,” to visit customers' facilities and visually read the commodity consumption data from the registers.
An advance in the art is the implementation of electronic registers. Electronic registers employ electronic hardware, such as solid-state devices and memory circuits, to register commodity consumption data measured by the electromechanical rotating disk. To obtain consumption information from the rotating disk, the electronic registers received pulse signals generated by an optical detector that detects rotations of the rotating disk. Each pulse represents a rotation (or part of a rotation) of the disk and thus also represents a quantity of energy consumed.
The electronic register meters, or at least the meters configured to generate pulses representative of consumed energy, allow for the implementation of automatic meter reading (“AMR”) equipment. AMR equipment is desirable because it eliminates the costs associated with traveling meter reading technicians. AMR devices include communication devices that obtain energy consumption data and communicate the data remotely to the service provider. Common AMR devices for residential meters operate to obtain the pulses generated by the meter, and periodically report a sum of the pulses to the service provider.
Electromechanical meters over time have evolved such that they produce output pulses in one or more of a few different standard formats or modes. While the general notion that a pulse represents a predefined quantity of energy is standard to each of the standard pulse formats, the shape and behavior of the pulses varies from pulse format to pulse format.
For example, some meters produce pulses in a return-to-zero format. Return-to-zero format pulses consist of a positive transition to a high state, and then a transition back to a low state after a predetermined “pulse period” or on-time. Other meters produce pulses in an alternating format. Alternating format pulses change from the current signal logic level to the opposite signal logic level, and then maintain that state until the next pulse is produced. The next pulse changes the signal level back to the first logic level.
In further detail, FIGS. 1a–3 show a number of pulse configurations that may be generated by electromechanical meters. For example, FIG. 1a shows a pulse train 10 including prior art “return-to-zero” pulses 11. Each pulse 11 has a first transition 12, a predetermined duration 14 at the new state, and a second transition 16 returning to the original state. In other words, a single pulse starts and ends at the original state, and typically has a predetermined or at least a minimum pulse period. FIG. 1b shows a similar pulse train 10′ in a reverse polarity mode, wherein originating state of each pulse 11′ is a high logic level instead of a low logic level. FIG. 2a shows a prior art “alternating state” pulse train 20 that consists of a series of pulses 21, 22, 23, 24, 25, 26 and 27 wherein each pulse merely changes the signal logic state and remains in that logic state until the next pulse. FIG. 2b shows a differential alternating state pulse train 25 which includes two identical pulse trains 26 and 27 having opposite polarity. The differential pulse train 25 is used in many meters and is often referred to as a KYZ pulse signal.
FIG. 3 shows a pair of pulse signals 32 and 34 that together generate a four state output signal consisting of a repeating sequence of 00, 01, 11, and 10. A four state sequence may be used to identify the direction of power flow. In particular, in some cases, power may flow in either direction. In a residential meter, for example, a customer may have an electricity generating windmill that in some cases actually provides net power to the service provider through the meter. A normal pulse generating electromechanical meter can not convey directional information, even though the rotating disk would be rotating in reverse. However, an electromechanical meter configured to provide a four state pulse signal would generate the sequence 10, 11, 01, 00 when running in reverse, and generate the sequence 00, 01, 11, 10 when running in the forward direction.
As discussed above, different meters may generate any of the above output pulse modes. Accordingly, AMR devices are typically designed to accept one or more of these pulse formats.
However, because not all AMR devices accept each pulse format, inefficiencies can result in attempting to match AMR devices with meters. In most cases, this problem may be addressed by purchasing appropriate AMR devices to accommodate the pulse formats employed by all or most residential meters in a particular service area.
It would be advantageous, however, to allow service providers many choices of AMR devices regardless of the pulse type the AMR devices are configured to read. Accordingly, there is a need for a metering arrangement that reduces the restrictions on the interface between available AMR devices and meters.